Piers Morgan has lashed out at Larry King after the former talk show host branded it a "mistake" to hire the British journalist as his replacement.

Morgan took over King's nightly interview programme on U.S. network CNN when the veteran stepped down in 2011, but the series was axed this year due to declining ratings following Morgan's ill-advised anti-guns crusade.

King believes CNN bosses made an error recruiting Morgan in the first place, telling radio DJ Howard Stern on Wednesday, "I thought they made a mistake in the Piers hire. I thought it was a mistake, one, to hire a Britisher (sic) in prime time and, two, I thought that he made himself too much part of the show."

Now Morgan has responded to the comments, firing back at King in a series of terse messages on Twitter.com.

He writes, "Hey Larry... you don't need to KEEP b---hing about me. It's over. Relax... And FYI (for your information)... there is no such word as 'Britisher'. But then research & facts were never your strong point were they, Brooklyner?

"Always tried to be respectful to @kingsthings - but he's been a constant poisonous twerp towards me for 3 years and I'm bored with it. As for our respective egos, one of us changed his name legally to 'King' and it wasn't me. So get over yourself @kingsthings. Why should I show any respect to @kingsthings any more when he has shown zero to me? Game on, Brooklyner."